Boiler apparatus for utilizing the waste gases from cement kilns



May 25,1926. 1,585,754,

G. Y. BONUS ET AL BOILER APNRATUS UTILIZING THE WASTE GASES FROM CEMENT KILNS Filed March 5. 1921 lllillllllll I I 5.- MM

Patented May 25, 1926.

UNITED STATES 1,585,754 PATENT OFFICE.

GEORGE Y. BONUS, OF CHICAGO, ILLINOIS, AND EDGAR KIDWELL, OF MILWAUKEE, WISCONSIN, ASSIGNORS, BY MESNE ASSIGNMENTS, TO KIDWELL BOILER COM PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

BOILER APPARATUS FOR UTILIZING THE WASTE GASES FROM CEMENT KILNS.

Application filed March 3, 1921.

The invention relates to an apparatus, including a water-tube steam boiler, for utilizing the waste heat from cement kilns. In prior apparatus the gaseous products from the kilns are introduced into the bottom of the structure within which the boiler is supported, and in consequence of the upward flow of such products toward the boiler surfaces the dust which is commingled with the gas has to be bodily lifted by the latter. This action not only impedes the flow of the gas, but a large amount of dust is blown amongst the boiler surfaces in such a manner as to settle upon the tubes and clog the spaces therebetween. Again, such dust as eventually falls to the bottom of the structure is of a temperature of 1200 degrees, Fahr. or more, and is therefore too hot to be handled by an off-bearing conveyer.

The object of our invention is to provide an apparatus of such construction that the heat units of the gases and dust escaping from cement kilns, are effectually utilized without substantial deposition of the dust on the boiler surfaces, and that the dust is effectually separated from the mixture and is brought to a condition which permits its safe removal and handling.

In the preferred form of embodiment of our invention we provide within the boiler supporting structure or setting a succession of heat passes whereof the first pass communicates at its lower end with the second pass, the second pass communicates at its upper end with a third 'pass, and the third pass- (where three passes are employed).

communicates at or adjacent its lower portion with an exhausting fan or other gas suction means. Where more than three passes are employed the additional passages succcssively communicate with each other similarly to the preceding passes; the final pass being likewise connected with the fan or suction means. Entering the upper portion of the first pass, in a plane below the water level of the boiler, is a conduit extending from the gas discharge of a cement kiln, the inflowing gas, by reason of the draft in duced by the fan or suction means, entering the upper portion of the first pass and flowing downward therein; thence upward and downward through the succeeding passes, and finally escaping through the fan or suction means. In its devious course Serial No. 449,472.

through the passes, the hot dust-laden gas impinges against the boiler tubes and their associated elements. Means are provided whereby the dust is effectually separated from the gas in its passage through the structure, whereby the dust is deposited in the bottom of the structure; whereby the dust deposits are rapidly removed; and whereby other practical advantages are attained; all of which will be hereinafter described and claimed.

Referring to the drawings- Figure 1 is a longitudinal vertical section of an apparatus embodying the principle of our invention.

Fig. 2 is a sectional elevation of a preferred form of exhasuting fan.

The supporting structure or setting comprises the front and back walls 10, 11, respectively, the side wall 12 and the roof 13.

The bottom is constructed with a pit which is preferably divided into two cells 14, 15 by an upstanding bridge wall 16 extending transversely of the setting. These cells open at one or both ends through either or both side wallsof the setting. The pit inclines upwardly from the cells toward the front and rear walls, as at 17 and 18 respectively, the forward incline 17, rising somewhat above the base of the front wall, as shown. Each of the cells is equipped with a suitable conveyer, such as the screw conveyer 19, whereby the accumulations in the cell can be delivered to the exterior of the casing.

The boiler which we have selected to illustrate our invention. is of the multiple drum and tubular bank. type wherein spacedapart transversely-arranged drums are associated with banks of water tubes. The mud drum 20 is located at the rear of the bridge wall; the water drum 21 is located mg a continuous circulation path for the water. The steam spaces of the drums 22, 23 are connected by tubes 28 which conduct the steam which is liberated from the water in the rear drum 22 to the steam space of the front drum 23, such steam during its passage through the tubes 28 being effectually dried or superheated. The drum 23 is provided with a steam discharge element. The water spaces of the drums 22, 28 are connected by tubes 29, '30 which constitute a supplemental path through which a portion of the water is diverted from the main path and circulated through the front drum 23 in such a manner as to ensure a constant level of water in the latter drum irrespective of the fluctuations of the water within the steam-disengaging drum 22 or other remote portion of the boiler, or the rate at which the boiler is being operated.

The boiler chamber constituted by the setting is provided with suitably-disposed forward and rearward baffles 31, 32 which provide three succeeding heat passes, the first and second passes being forward of the rear tube bank 27 and being in communication with each other at their lower portions and also with the forward cell 14; the second pass being in communication with the upper portion of the final pass, and the latter being in communication at its lower portion with the cell 15 and also with the outlet 33 in the rear wall of the setting. This outlet communicates with the inlet of an exhausting fan or suction means which cause a forced draft throughout the respective passes.

Opening into the upper portion of the front wall 10, in the space between the drums 21, 28 and therefore below the water level of the boiler, is a horizontal conduit 35 extending from the discharge this of a cement kiln. This conduit is provided with a regulating damper 86 by the proper adjustment of which the conduit can be opened, and the dustladen gas emitted from the kiln thus be delivered in large volume, at a temperature which usually averages from 1200 to 1500 Fahin, into the upper pass and against the boiler surfaces therein; such gas thus flowing through the 'suc ceeding passes and in contact with the op posing boiler surfaces by the forced draft, as indicated by the arrows in Fig. 1. hen the gas is introduced into and across the upper portion of the first pass, the gas is caused to flow downward, and hence the dust, dropping, does not impede the flow of the gas. The incoming gas sweeps along the cement dust admixed therewith, and due to that action and the gravitation of the dust, the dust has a high velocity which projects it down upon the inclined surface 17, whence the dust slides down to the cell 14. Tl1e dust delivered to the first pass flows upon and over the surfaces of the tubes exposed thereto, and therefore the heat is extracted from the dust as well as from the gas. Hence when the dust reaches the cell 14 the temperature of the dust is reduced so low that the material can be safely handled by the conveyor.

The gas continues its travel to and through the second and third passes, as indicated by the arrows, and finally reaches the outlet 38 where it enters the exhausting fan 34 and escapes thence through the stack 3 This stack is provided with a suitable damper Any dust carried by the draft into the second pass and falling, drops into the cell 14, and likewise any dust which the as carries into the third pass and falling, drops into the cell 15, the dust deposits in each case being expelled by the conveyer.

The baffle 81 preferably terminates somewhat short of the roof of the boiler so as to permit the flow of ascending gases in close relation to the superheater tubes 28 and between the passes.

The lower portion of the first pass is preferably equipped with a deflector 40, comprising usually a curved gate hinged at one end, as at 41, tothe adjacent baffle, so that the deflector can be adjusted to an angle effective to throw the dust toward any posl tion along the inclined surface 17, as may be required by the amount of the dust content of the mixture.

The fan 34 is preferably constructed with a peripheral outlet 42 which is so located that any dust that may be carried along by the gas into the fan is thrown by the centrifugal force toward and into the outlet. This outlet, which is controlled by a damper 43, is connected by means of a pipe 44 with a pipe 45 leading into the front pass adjacent the upper end of the inclined floor 17. The pipe 45 is equipped with a regulating damper lVhen this damper is in open position the dust entering the outlet 42 is impelled tow rd and delivered into the chamber at the front of the boiler setting.

li hen the cement kilns are discharging a relatively small volume of gas, the flow of the gas through the heat passes of the boiler is proportionally slow, and in consequence the gas becomes stagnant and large quantities of dust settle upon the boiler surfaces. To overcome this objection we connect the gas delivery conduit 35, adjacent its discharge portion, with the inlet pipe 45 at the front of the setting, by means of a pipe 47 provided with a suitable damper 48, by the manipulation of which the communication between the pipe 45 and the conduit can be opened or closed, as desired. lVhen the damper 48 is in open position, and the damper 46 is closed, a portion of the exhaust gas, instead of escaping by way of the stack, is directed by the, action of the fan through the pipes 44, 45 and 47 into the conduit, (as indicated by the arrow 49) and thence into the upper portion of the first heat pass within the setting. The volume and pressure of the exhaust gas thus returned injects into the first heat pass, at a sufficient velocity to prevent stagnation, the gas flowing from the kilns. Or in other words, during the slack period enough of the exhaust gas is returned to ensure in conjunction with the entering gas from the kiln a velocity sufficient to sweep the dust from the boiler surfaces; and by the action of the fan this gas is churned through the heat passes until the kiln is ready to deliver the full complement of gas to the boiler for efiicient operation.

It is to be understood that we do not limit our invention to the particular from of embodiment thereof herein disclosed, as the construction may be modified within the principle of the invention and the scope of the appended claims.

lVe claim 1. In an apparatus for the purpose described, a water-tube steam boiler having a series of succeeding heat passes whereof the first pass communicates at its lower end with the second pass, a discharge conduit for hot dust-laden gases leading into the upper portion of the first pass, means for establishing a forced draft through the passes, and means whereby dust carried over with the exhaust gas from the final pass is returned to the first pass.

2. In an apparatus for the purpose described, a water-tube steam boiler having a series of succeeding heat passes whereof the first pass communicates at its lower end with the second pass, a discharge conduit for hot dust-laden gases leading into the upper portion of the first pass, a centrifugal fan connected with the final pass and arranged to establish a forced draft through the passes, and a pipe connection between the fan and the lower portion of the first pass whereby dust carried over to the fan is returned to the said pass.

3. In an apparatus for the purpose described, a water-tube steam boilerhaving a series of succeeding heat passes whereof the first pass communicates at its lower end with the second pass, a discharge conduit for hot dust-laden gases leading into the upper portion of the first pass, means for establishing a forced draft through the passes, and means, including pipe connections and con trolling devices therefor, whereby the dust expelled from the final pass can be returned to the first pass, and whereby the exhaustgases can be returned to the conduit to increase the velocity of the entering gases.

l. In an apparatus for the purpose cescribed. a water-tube steam boiler having a series of succeeding heat passes whereof the first pass communicates at its lower portion with the second pass, a dust settling cell below said passes, an inclined fioor leading to said cell, an adjustable deflector at the lower portion of the first pass, a discharge conduit for hot dust-laden gases leading into the upper portion of the first pass, and means for establishing a forced draft from the first pass to and through succeeding passes.

5. In an apparatus for the purpose de scribed, the combination with a water-tube steam boiler of the multiple drum and tubuar bank type, including a front water drum and a front steam-and-watcr drum located above said water drum, a boiler supporting structure having a pit below the boiler, and baffling arranged to provide succeeding heat passes from the front to the rear of the structure, the first pass communicating at its lower end with the second pass and with the pit, of a discharge conduit for hot dust-laden gases leading into the first pass in the space between the said front drums, and means for establishing a forced draft from the first pass to and through the succeeding passes, the draft in the first pass being downward.

6. I11 an apparatus for the purpose described, the combination with a water-tube steam boiler of the mulitple drum and tubular bank type, including a front water drum and a front steam-and-water drum located above said water drum, a boiler supporting structure having a pit below the boiler, a wall dividing the pit into two dust settling cells, baffling arranged to provide succeed ing heat passes from the front to the rear of the structure, the first and second passes communicating at their lower ends with each other and with. one of said cells, the seecond pass communicating at its upper portion with the third pass, and the third pass communicating at its lower end with the other one of said cells, of a discharge conduit for hot dust-laden gases leading into the first pass in the space between the said front drums, and means for establishing a forced draft from the first pass to and through the succeeding passes, the draft in the first pass being downward.

7. In an apparatus for the purpose de scribed, the combination with a water-tube steam boiler of the multiple drum and tubular bank type, including a front water drum and a front stea-m-and-water drum located above said water drum, a boiler supporting structure having a pit below the boiler, and bafiiing arranged to provide succeeding heat passes from the front to the rear of the structure, the first pass communicating at its lower end with the second pass and with the pit, of a discharge conduit for hot dustladen gases leading into the first pass in the space between the said front drums, a contrifugal exhausting fan connected with the final pass and having a secondary peripheral outlet, an inlet pipe leading into the lower portion of the first pass, and a pipe connection between the said secondary outlet and the inlet pipe.

8. In an apparatus for the purpose described, the combination with a WatC-1t11b8 steam boiler of the multiple drum and tubular bank type, including a front water drum and a front steani-and water druni located above said Water druni, a boiler supporting structure having a pit below the boiler, and batliing arranged to provide succeeding heat passes from the front to the rear of the structure, the first pass communicating at its lower end with the second pass and with the pit, or a discharge conduit for hot dustladen gases leading into the first pass in the space between the said front drums, a centrifugal exhausting "fan connected with the final pass and having a secondary peripheral outlet, and a pipe connection between said outlet and the said conduit, and means for opening and closing the said pipe connection- GEORGE Y. BONUS. EDGAR KIDlVELL. 

